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(1)|-1/2|-根号9+(π+4)^0-sin30°+1/(根号2-1)

来源:学生作业帮 编辑:神马作文网作业帮 分类:数学作业 时间:2024/11/18 15:59:37
(1)|-1/2|-根号9+(π+4)^0-sin30°+1/(根号2-1)
(2)|-2|-4sin45°-(1/2)^(-2)+2根号2-(根号3-根号2)^0
(3)求值:(1-1/(a-1))÷(a^2-4a+4)/(a^2-a)其中a=-1
(4)先化简再求值:(a^2+6a+9)/(a^2-16)÷(a+3)/(2a-8)-(2a)/(a+4),其中a=2
(5)因式分解(1)9x^2-y^2-4y-4(2)2a^2-4a+2
(1)|-1/2|-根号9+(π+4)^0-sin30°+1/(根号2-1)
(1)|-1/2|-根号9+(π+4)^0-sin30°+1/(根号2-1)
=1/2-3+1-1/2+根号2+1
=根号2-1
(2)|-2|-4sin45°-(1/2)^(-2)+2根号2-(根号3-根号2)^0
=2-2√2-√2+2√2-1
=-1
(3)求值:(1-1/(a-1))÷(a^2-4a+4)/(a^2-a)其中a=-1
=(a-2)/(a-1)×a(a-1)/(a-2)²
=a/(a-2)
代入a=-1,-1/(-1-2)=1/3
(4)先化简再求值:(a^2+6a+9)/(a^2-16)÷(a+3)/(2a-8)-(2a)/(a+4),其中a=2
=(a+3)²/(a-4)(a+4)×2(a-4)/(a+3)-2a/(a+4)
=2(a+3)/(a+4)-2a/(a+4)
=6/(a+4)
代入a=2得6/(a+4)=1
(5)因式分解
(1)9x^2-y^2-4y-4
=(3x)^2-(y+2)^2
=(3x-y-2)(3x+y+2)
(2)2a^2-4a+2
=2(a^2-2a+1)
=2(a-1)^2